Increasingly lightweight fillers have recently been used in the formulation of hydraulically setting mortars, such as tile adhesives. This makes it possible to increase the mixing water requirement and reduce the density of the mixed mortar, which gives rise to an easily appliable, very productive mass. In order to obtain such characteristics, generally use is made of higher proportions of up to 20% or higher of relatively expensive lightweight fillers.
EP 985 646 A1 describes Portland cement-based masonry mortars containing a lightweight aggregate. Through the choice of a suitable screen fraction of the dense rock and also the porous lightweight aggregate, it is possible to provide a mortar solving the hole bridging problem. Cellulose ethers and in particular setting retarders can be used, but are not absolutely necessary.
EP 990 628 A1 describes a dry mortar mixture for producing a lightweight masonry mortar, which essentially contains cement, air-entraining additives and selected lightweight aggregates such as perlite and expanding glass and in particular the bulk density and particle size of the perlite and expanding glass must satisfy narrow criteria and must always be used together in large quantities. This gives rise to a lightweight masonry mortar fulfilling the requisite compressive strength characteristics and which additionally has an improved thermal insulation capacity. Setting retarders are not used.
EP 646 100 A1 describes a plaster and/or a colouring product for use on a facade containing as the hydraulically setting component solely aluminate cement (high-alumina cement). In order to slow down the resulting very rapid hydration, use is also made of trisodium citrate as a setting retarder. As fillers it is inter alia possible to use lightweight fillers, the filler proportion of 60 to 95 wt.-% being very high. Efflorescences can be drastically reduced due to the rapid setting. No distinction is made between fillers and lightweight fillers and the quantity ranges of the individual components and precise formulation details are not given.
DE 103 15 865 B3 describes hydraulically setting tile adhesives containing a metakaolin component. This can also be used in formulations with lightweight fillers in order to obtain the requisite adhesive tensile strength characteristics and deformability characteristics according to DIN EN 12002 of 2.5 mm or higher. There is no need to use cellulose ethers and in particular lightweight fillers and setting retarders.
The problem of the present invention is to provide a hydraulically setting mortar composition in which the action of lightweight fillers is increased by a multiple without having to accept losses with regards to the freshly mixed mortar characteristics such as processability, stability, setting behaviour, high productiveness and increased mixing water requirement. This is intended to provide a cost effective formulation with constant characteristics, which also leads to logistic advantages, because the voluminous lightweight filler can e.g. be replaced by compact quartz sand. It must additionally be possible to improve the correctability, open time and/or physical mortar characteristics such as adhesive tensile strength and horizontal deformation of the completely hardened mortar. A premix is also to be made available by means of which the lightweight filler or a large part thereof in mortar compositions can be replaced in order to obtain the indicated advantages of the mortar composition in a simple manner, also in the case of existing formulations. By means of such a premix, a user must be able to bring about a formulation adjustment or adaptation with very low development costs, the use characteristics with lower raw material and production costs remaining the same or can even be improved. Such a premix is also to be used in order to significantly improve the characteristics profile of mortar formulations without lightweight fillers through the use of a premix and without high development costs, so that the typical processing characteristics for lightweight filler-containing mortars are maintained.